Move to busybox for smaller images, allow to configure the docker registry in builds

Dockerfile

@@ -1,4 +1,6 @@
-FROM node:16 as frontend-builder
+ARG DOCKER_IO=docker.io
+
+FROM ${DOCKER_IO}/library/node:16 as frontend-builder
 
 WORKDIR /micro
 
@@ -8,7 +10,7 @@ RUN npm install -g @angular/cli && \
     npm install && \
     npm run build
 
-FROM golang:1.19 as backend-builder
+FROM ${DOCKER_IO}/library/golang:1.19 as backend-builder
 
 WORKDIR /micro
 
@@ -21,10 +23,13 @@ RUN go install github.com/swaggo/swag/cmd/swag@latest && \
     fileb0x b0x.yaml && \
     CGO_ENABLED=0 GOOS=linux go build -a -installsuffix cgo -o dashboard .
 
-FROM alpine:latest
+FROM ${DOCKER_IO}/library/busybox:latest
 
-WORKDIR /usr/local/bin
+# Copy certs and passwd from builder
+COPY --from=backend-builder /etc/ssl/certs/ca-certificates.crt /etc/ssl/certs/
+COPY --from=backend-builder /etc/passwd /etc/passwd
 
+WORKDIR /usr/local/bin
 COPY --from=backend-builder /micro/dashboard .
 
 EXPOSE 80